1. Field of the Invention
The present invention relates to a wire-winding device having a circuit unit. In particular, this invention relates to a wire-winding device having a circuit unit that can adjust the length of the cable and convert the voltage and current.
2. Description of the Related Art
The computers, the printers, or the communication devices (such as telephones or fax machines) are connected by a cable to transmit the electric signals or the data. However, a cable is too long so that the cable will be intertwisted or the cable is too short is a problem for the user. Therefore, a variety of wire-winding devices are developed, such as the wire-winding devices disclosed in U.S. Pat. No. 6,416,355 and 6,808138. The wire-winding device of the prior art includes a body, a cable, a wire-winding disk and a volute spring. The plug of the cable is plugged into the socket of the communication devices to transmit the data, and the length of the cable can be adjusted.
However, the wire-winding boxes or the wire-winding devices of the prior art merely have the wire-winding function and the signal-transmitting function. They cannot convert the voltage or the current. Furthermore, when the cable is wound onto the wire-winding device, the winding disk often touches the housing, so that the occurring friction affects the wire-winding speed, causing inconvenience.